Welding stainless steel

[Steve g]

Fellas,
I have a factory exhaust manifold off a 4.0l Jeep that is a tubular steel (header style) that I believe may be stainless steel. If it is, can I weld up the cracks in it with a 115V/125 A Lincoln MIG welder? Are there any special precautions or procedures? What about the wire type? Or, should I just take it to someone with a tig?
Thanks again guys.
Steve g.

[Brian_B]

I do not know if a welder that small would weld stainless. Check the parent site for specks.

http://www.lincolnelectric.com/


You have to use the correct wire for the type of stainless it is. I would bet its 304 (cheap grade) like most of the other automotive products I see. Then again the you will need the gas. There may be some sort of shielded stainless wire, but I am not familiar with it.

Check the manifold with a magnet. If its non-magnetic its probably stainless. I can't see them every using aluminum on an exhaust manifold.

Welding thin stainless is not the easiest thing in the world in the first place, but if you have never done it before this might be a hard place to start.

If you machine is capable of it (check) and you have the gas and wire, you could give it a try. I would think either replacing it from a salvage yard or getting a shop to TIG weld it would be cheaper and faster.

A TIG is what most of the "custom shops" use. Ever watch the discovery channel? Both bikes and cars are done this way.

Is that all as clear as mud now? Sorry.

Brian

[PetesPonies]

I've welded stainless with the same setup that I weld carbon steel with. I have not seen a concernable difference.

[Steve g]

Went to the Lincoln site and read a few articles then decided to try it with the current wire/gas setup. Cranked the heat up and it worked great, "slicker than deer guts on a door knob" as the say up in these parts.
I do believe it was a very low grade stainless, if it was stainless at all. Most of it had a light coat of rust with only a few spots where clean metal could be seen. Truck is '89 Jeep, so the fact that there were any clean spots leaf me to believe it was stainless.
Steve g

[Harry Phinney]

For future reference, welding stainless will actually require slightly less heat than welding normal carbon steel due to stainless' lower thermal conductivity (i.e. the heat doesn't spread out from the weld zone quite as quickly). Using normal mild steel wire (e.g. ER70S6) and gas such as C25 (75% Ar, 25% CO2) will work, but the weld will rust more quickly than if it were welded with stainless wire. There are also special gas mixes that work better, and for the best corrosion resistance the heat-affected-zone should be passivated after welding. The passivation is typically done with some pretty nasty acid pastes.

Harry Phinney

[PetesPonies]

yep, the stainless used on my OEM exhaust is very low grade and does get a slight covering of rust coloring.